Employee Benefit Plans (Components Of Pension Expense) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
BancShares Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 3,220	$ 3,600
Interest cost	7,180	6,748
Expected return on assets	(9,159)	(8,295)
Amortization of prior service cost	52	53
Amortization of net actuarial loss	1,600	2,833
Total pension expense	2,893	4,939
Bancorporation Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	650	933
Interest cost	1,675	1,628
Expected return on assets	(2,779)	(2,869)
Total pension expense	$ (454)	$ (308)